Though I haven't tried the CSP2 with the SE84C, I have with four different models of the EL34 amps. And love the benefits of what Steve calls "riding the gain." He goes into detail about this in the Owner's Manual for the ZStage. Here are excerpts:

THE MAGIC OF GAIN By now if you don’t own one of the rare amplifies that requires more than 2 volts to come to full power, you’re probably wondering what possible advantages could there be to using a ZSTAGE? Gain = Dynamics. The more dynamic your music is, the more real it will sound. Adding a ZSTAGE to your source will increase it’s dynamics and overall presence. In fact the difference can be such that the sound of your source will improve so much your thoughts about upgrading it will melt away. A customer recently purchased a new CD player of considerable cost and reputation to replace his existing player. The new player was better in every way and justified it’s much higher price. Then the player broke and the customer was forced to go back to his old player. Sadness... then he remembered he had a ZSTAGE in a different system, and placed it between his old CD player and his preamp hoping it would make it sound better. In fact it did, so much so that he could tell no difference between this combination and the new player he had. An example of how gain could save you a couple thousand dollars! RIDING THE GAIN A term we came up with because of the active nature of the adjustment process that can take place when you use a ZSTAGE in conjunction with an preamp OR amplifier fitted with a gain control. Riding the gain happens when you have two controls. One at the source and one at the amp or preamp. Think of it like water pressure. You have a pipe with a valve at the input end and another valve at the output end. The valves represent the gain controls and the pipe represents the signal path between the two gain gain controls. By turning up the input valve and turning the output valve down we create pressure inside the pipe. By turning down (closing) the input valve and turning up (opening) the output valve we reduce pressure inside the pipe. So if you took a garden hose and turned on the faucet you would have lots of water coming out the end, but it wouldn’t be able to spray anything until you put a nozzle on the end. The nozzle acts like a valve to restrict the output causing the pressure in the hose to increase. PRESSURE in this metaphor is the same thing as DYNAMICS in your stereo system.

FREQUENCY BALANCE By having a gain control at the source and a second one at the amp (or preamp) it is possible to manipulate the dynamics of your music and it’s overall frequency balance. For example, if the music sounds thin you can increase the “pressure” by turning down the gain control on the amplifier (or preamp) and then raising the gain control at the source. This will add noticeable weight to the music and mellow out the top end. On the other side, if the music is sounding boomy or thick, you can do the opposite - turn up the gain on the amp and reduce the gain at the source. The boominess will go away.

Guys, thanks so much for all of your information. I am also wondering whether I may use a 6N2P in SE84C. If so, how will the 6N2P make SE84C sound? Kindly note that mine is an older SE84C and I am not sure whether it will make a difference. Thanks.

Rivieraranch, I missed your reply until now, sorry. I also did not want to boycott someone else's original thread. But, could you please elaborate?

The way I see it, even if the M-T is a high-gainer to start with, theoretically it can also be used on a 'riding the gain' configuration, as it would only be a matter of adjusting for the proper initial volume settings, isn't it?

I mean, part of the motivation I can anticipate for this mode in the M-T is precisely the fact that one can limit the effects of its high gain if the music source is heavy and boomy, for example. In this scenario, a lower gain setting on the ZStage may limit this effect.

The other possibility I see is for increasing music source dynamics. I would in this case limit the volume setting on the M-T and increase the ZStage gain, to boost that build-up 'pressure' that conveys better dynamics.

In other words, the concept is the same, just a matter of adjusting the proper gains as required, not unlike what you and Zygi described earlier with the CSP2+ and the SE84C. In the particular case of the M-T, more care should be taken when adjusting that volume knob though.

I'm just beginning to ride the gain with my MINI TORII and CSP2+. One way is to boost the MT volume all the way and use the volume switch on the CSP2+. Another way is to turn the MT volume up 1/3 and use the CSP2+ to back up the sound and create some increased dynamics. I have not reached a happy medium yet, so I am unable to say anything definitive.

I understand there's no such happy medium, though. You either go one way or the other, depending on your objectives for the particular music source selection involved at the time. Give it a try playing the music source selections that you know would either require more dynamics or that sound boomy or too much 'in your face'.

Both these opposite conditions can be improved by 'riding the gain' the proper way. The first method you mentioned is for a boomy (in your face) recording, the second one for recordings requiring more dynamics.

In both cases, you should get a tangible improvement. Just a suggestion.